Department of Pure and Applied Sciences, University of Urbino Carlo Bo, Via Ca' Le Suore 2/4, 61029, Urbino, Italy; Department of Earth Sciences, University of Florence, Via G. La Pira 4, 50121, Florence, Italy.
Institute of Geosciences and Georesources (IGG), National Research Council of Italy (CNR), Via G. La Pira 4, 50121, Florence, Italy.
J Environ Manage. 2023 Dec 15;348:119383. doi: 10.1016/j.jenvman.2023.119383. Epub 2023 Oct 22.
Water quality indices (WQIs) are numeric parameters that summarize the overall quality status of freshwaters compared to quality standards by aggregating multiple physicochemical data into a single value. Among the available WQIs in the literature, several criticalities were recognized including: (a) mathematical complexity of the computation, (b) lack of inclusivity, (c) arbitrary weight assignment method, and (d) site-specificity of most of the indexes. The proposed index, the Chemical Water Quality Index (CWQI), aims to overcome these flaws and provides a computation based on simple mathematic equations that are easily manageable on spreadsheet software. The computation is divided into two steps: (i) parametrization of the variables and (ii) index determination. The parametrization consists of assigning a score (s) from ∼1 to 10 to each chemical variable based on (i) measured concentrations and (ii) quality targets (e.g., the limits provided by the European legislation for drinking waters). In the second step, a weight (w), directly proportional to the score (s), is assigned to each parameter, allowing to overcome any bias related to subjective assignments from the user. The resulting CWQI ranges from ∼1 (very good quality) to 10 (extremely poor quality). The reliability and accuracy of the CWQI were assessed by (i) applying the computation to 1,810 waters and (ii) comparing our results with another available WQI. The CWQI outputs showed an optimal response with the number of variables exceeding the quality target with high correlation coefficients (r = 0.94; R = 0.89). Due to the simplicity of its computation, the absence of arbitrariness in the weightage of selected variables, and the independence of the proposed approach regarding the choice of the chemical parameters, CWQI can be easily and universally applied.
水质指数（WQIs）是将多个物理化学数据聚合为一个单一值，以比较淡水的整体质量状况与质量标准的数值参数。在文献中可用的 WQIs 中，已经认识到了一些关键问题，包括：（a）计算的数学复杂性，（b）缺乏包容性，（c）任意的权重分配方法，以及（d）大多数指数的特定于地点的性质。提出的指数，即化学水质指数（CWQI），旨在克服这些缺陷，并提供基于简单数学方程的计算，这些方程可以在电子表格软件上轻松管理。计算分为两个步骤：（i）变量的参数化和（ii）指数的确定。参数化包括根据（i）测量浓度和（ii）质量目标（例如，欧洲法规为饮用水规定的限制），为每个化学变量分配一个从 ∼1 到 10 的分数（s）。在第二步中，为每个参数分配一个权重（w），与分数（s）成正比，从而克服了与用户主观分配相关的任何偏差。所得的 CWQI 范围从 ∼1（极好的质量）到 10（极差的质量）。通过（i）将计算应用于 1810 种水，以及（ii）将我们的结果与另一个可用的 WQI 进行比较，评估了 CWQI 的可靠性和准确性。CWQI 的输出显示出与质量目标的变量数量超过的最佳响应，具有高相关系数（r=0.94；R=0.89）。由于其计算的简单性，所选变量权重的任意性不存在，以及所提出的方法对化学参数选择的独立性，CWQI 可以轻松且普遍地应用。
